Countersink.



No. 727,580. Y PATENTED MAY 12, 1903.

G.W.BRAGK1N.

COUNTER-SINE'. APPLIoATloN FILED imm 1s, 1902.

:I0 MODEL.

.L LE; `1:11:51;

'Nin STATES Patented May 12, 1903.

PATENT OFFICE.

COUNTERSINK.

SPECIFICATION forming part of Letters Patent N o. 727,580, dated May 12, 1903.

Application iiled .Tune 18, 1902. Serial No. 112,191. (No model.)

.T0 cir/ZZ when?, it may concern.-

Be it known that I, GEORGE W. BRACKIN, a citizen of the United States, residing at Philadelphia, in the county of Philadelphia and State of Pennsylvania,have invented certain new and useful Improvements in Countersinks; and I do declare the following to be a full, clear, and exact description of the in vention, such as will enable others skilled in the art to which it appertains to make and use the same, reference being had to the accompanying drawings, and to the figures of reference marked thereon, which form a part of this specification.

My invention relates to countersinks, more particularly to devices for attachment to drills and auger-bits, whether manually or powerdriven, by means of which the customary conical depression for a screw-head may be formed at the top or mouth of a bore of any desired depth without removing the boringtool. Such devices act also as gages of depth of holes drilled.

Each constituent element ot' my invention is described in detail and its individual office, together with the mode of operation of the whole, fully explained in this specification.

I accomplish the object stated by constructing and associating the parts as shown in the accompanying drawings, of which- Figure 1 is a front view of my invention attached to'a boring-tool. Fig. 2 represents a view from one side. Fig. 3 is a similar view from the opposite side. Fig. 4. is a representation of one of the twin cutters detached, and Fig. 5 shows one of the two sides or clamping-blocks by itself.

Like numerals refer to like parts in the several views.

Considering the drawings, numeral l marks a boring-tool of any character and Within certain limits of any diameter. At a desired point of the length of tool l my invention can be secured, thus gaging the depth of the hole bored.

Numerals 2 and 3 designate the duplicate Each of the sides 2 and 3 has formed within it at about the middle an inclined cutterseat. In Fig. 5 the side 3 is illustrated, showingits inclined cutter-seat, (marked 6.) The side 2 as ordinarily constructed is precisely the same in shape. The edge only of its cutter-seat is shown in the drawings,(designated by number 7.)

Within the cutter-seats in the sides are secured the cutters 8 and 9 by means of the screws 10 and 1l. The cutters are customarily twins and have in commonthe shape 'set out in Fig. et. Thecutters have the rectangular body portions, through which holes are bored for the screws 10 and 11. The hole appearing in Fig. 5 through side 3 is marked 1.2. Other features are the cutting edges (designated 13 and 14) and the rounded backs 15 and 16.

From Figs. 2 and 3 it will be observed that the lower ends of the inclined cutters project slightly into the twists or helical channels of the drill, and this fact permits the cutters to enter the hole bored and then commence cutting away the edge of the hole as the tool is rotated.

It is found to be advantageous to equip my invention with the L-shaped stop 17, in the shank of which is a longitudinal slot 1S, through which one of the clampingscrews for example, screw 4-passes The slot 18 permits some vertical adjustment of the stop and limits the size of the countersink, at the same time preventing further entrance of the drill into the hole.

My invention as illustrated is designed for a woodworking eountersink; but the cutters could be hardened and strengthened for use in metal.

I do not limit myself to the precise pattern of any of the parts shown and`described,but may modify their special shapes, if so desired.

I am aware that countersinks for attachment to boring-tools have been made, and I also know that in one or more instances the cutter has been inclined, and I do not claim that feature broadly.

Vhat I claim, and seek to protect by Letters Patent of the United States, is

In a countersink, the combination of the rectangular clamping-blocks arranged paral- IOO lel to eachother, clamping-screws passing thereby securing the cutters removably in 1o through the said blocks near their ends and their seats, substantially as described.

adapted to clamp the blocks upon a, boring- In testimony whereof I affix my signature tool, each ofxthe said blocks being provided in presence of two witnesses.

exteriorly at its middle point with a, cutterseat inclined downwardly and inwardly, du- GEORGE W BRACKN plicate and interehangeablecutters construet- Witnesses: ed to it the said seatsiu the b1ooks,and screws EVERETT ANDREWS,

passing throughthe cutters into the blocks MYRON H. ALLEN. 

